Trouble controlling where to add Faces on my model
The problem is that you're creating one big ngon with that mesh. Blender doesn't work well with ngons and wants tris (three-sided faces) or more preferably, quads (four-sided faces).

Break your mesh down into smaller segments that accommodate Blender's needs. If I were you, I'd just make one big plane and then subdivide it enough that you can form the same mesh by angling rows and columns of vertices to get your desired pattern, and then delete the faces that you don't want. Your mesh pattern is repetitive, so you only really need to create one section of it and then duplicate it as much as you need and merge them all together into a larger mesh.

Here's an example I threw together for you. You can bevel the angled edges to make them more rounded before you duplicate and merge the meshes together into a larger mesh. 

http://www.pasteall.org/blend/42020